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packages/nodes-base/nodes/Facebook/FacebookTrigger.node.ts

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+import { snakeCase } from 'change-case';
+import { createHmac } from 'crypto';
+import type {
+	IDataObject,
+	IHookFunctions,
+	ILoadOptionsFunctions,
+	INodePropertyOptions,
+	INodeType,
+	INodeTypeDescription,
+	IWebhookFunctions,
+	IWebhookResponseData,
+	JsonObject,
+} from 'n8n-workflow';
+import { NodeApiError, NodeConnectionTypes, NodeOperationError } from 'n8n-workflow';
+import { v4 as uuid } from 'uuid';
+
+import { facebookApiRequest, getAllFields, getFields } from './GenericFunctions';
+import type { FacebookWebhookSubscription } from './types';
+
+export class FacebookTrigger implements INodeType {
+	description: INodeTypeDescription = {
+		displayName: 'Facebook Trigger',
+		name: 'facebookTrigger',
+		icon: 'file:facebook.svg',
+		group: ['trigger'],
+		version: 1,
+		subtitle: '={{$parameter["appId"] +"/"+ $parameter["object"]}}',
+		description: 'Starts the workflow when Facebook events occur',
+		defaults: {
+			name: 'Facebook Trigger',
+		},
+		inputs: [],
+		outputs: [NodeConnectionTypes.Main],
+		credentials: [
+			{
+				name: 'facebookGraphAppApi',
+				required: true,
+			},
+		],
+		webhooks: [
+			{
+				name: 'setup',
+				httpMethod: 'GET',
+				responseMode: 'onReceived',
+				path: 'webhook',
+			},
+			{
+				name: 'default',
+				httpMethod: 'POST',
+				responseMode: 'onReceived',
+				path: 'webhook',
+			},
+		],
+		properties: [
+			{
+				displayName: 'APP ID',
+				name: 'appId',
+				type: 'string',
+				required: true,
+				default: '',
+				description: 'Facebook APP ID',
+			},
+			{
+				displayName: 'To watch Whatsapp business account events use the Whatsapp trigger node',
+				name: 'whatsappBusinessAccountNotice',
+				type: 'notice',
+				default: '',
+				displayOptions: {
+					show: {
+						object: ['whatsappBusinessAccount'],
+					},
+				},
+			},
+			{
+				displayName: 'Object',
+				name: 'object',
+				type: 'options',
+				options: [
+					{
+						name: 'Ad Account',
+						value: 'adAccount',
+						description: 'Get updates about Ad Account',
+					},
+					{
+						name: 'Application',
+						value: 'application',
+						description: 'Get updates about the app',
+					},
+					{
+						name: 'Certificate Transparency',
+						value: 'certificateTransparency',
+						description: 'Get updates about Certificate Transparency',
+					},
+					{
+						name: 'Group',
+						value: 'group',
+						description: 'Get updates about activity in groups and events in groups for Workplace',
+					},
+					{
+						name: 'Instagram',
+						value: 'instagram',
+						description: 'Get updates about comments on your media',
+					},
+					{
+						name: 'Link',
+						value: 'link',
+						description: 'Get updates about links for rich previews by an external provider',
+					},
+					{
+						name: 'Page',
+						value: 'page',
+						description: 'Page updates',
+					},
+					{
+						name: 'Permissions',
+						value: 'permissions',
+						description: 'Updates regarding granting or revoking permissions',
+					},
+					{
+						name: 'User',
+						value: 'user',
+						description: 'User profile updates',
+					},
+					{
+						name: 'Whatsapp Business Account',
+						value: 'whatsappBusinessAccount',
+						description: 'Get updates about Whatsapp business account',
+					},
+					{
+						name: 'Workplace Security',
+						value: 'workplaceSecurity',
+						description: 'Get updates about Workplace Security',
+					},
+				],
+				required: true,
+				default: 'user',
+				description: 'The object to subscribe to',
+			},
+			//https://developers.facebook.com/docs/graph-api/webhooks/reference/page
+			{
+				displayName: 'Field Names or IDs',
+				name: 'fields',
+				type: 'multiOptions',
+				typeOptions: {
+					loadOptionsMethod: 'getObjectFields',
+					loadOptionsDependsOn: ['object'],
+				},
+				default: [],
+				description:
+					'The set of fields in this object that are subscribed to. Choose from the list, or specify IDs using an <a href="https://docs.n8n.io/code/expressions/">expression</a>.',
+			},
+			{
+				displayName: 'Options',
+				name: 'options',
+				type: 'collection',
+				default: {},
+				placeholder: 'Add option',
+				options: [
+					{
+						displayName: 'Include Values',
+						name: 'includeValues',
+						type: 'boolean',
+						default: true,
+						description: 'Whether change notifications should include the new values',
+					},
+				],
+			},
+		],
+	};
+
+	methods = {
+		loadOptions: {
+			// Get all the available organizations to display them to user so that they can
+			// select them easily
+			async getObjectFields(this: ILoadOptionsFunctions): Promise<INodePropertyOptions[]> {
+				const object = this.getCurrentNodeParameter('object') as string;
+				return getFields(object) as INodePropertyOptions[];
+			},
+		},
+	};
+
+	webhookMethods = {
+		default: {
+			async checkExists(this: IHookFunctions): Promise<boolean> {
+				const webhookUrl = this.getNodeWebhookUrl('default') as string;
+				const object = this.getNodeParameter('object') as string;
+				const appId = this.getNodeParameter('appId') as string;
+
+				const { data } = (await facebookApiRequest.call(
+					this,
+					'GET',
+					`/${appId}/subscriptions`,
+					{},
+				)) as { data: FacebookWebhookSubscription[] };
+
+				const subscription = data.find((webhook) => webhook.object === object && webhook.status);
+
+				if (!subscription) {
+					return false;
+				}
+
+				if (subscription.callback_url !== webhookUrl) {
+					throw new NodeOperationError(
+						this.getNode(),
+						`The Facebook App ID ${appId} already has a webhook subscription. Delete it or use another App before executing the trigger. Due to Facebook API limitations, you can have just one trigger per App.`,
+						{ level: 'warning' },
+					);
+				}
+
+				return true;
+			},
+			async create(this: IHookFunctions): Promise<boolean> {
+				const webhookData = this.getWorkflowStaticData('node');
+				const webhookUrl = this.getNodeWebhookUrl('default') as string;
+				const object = this.getNodeParameter('object') as string;
+				const appId = this.getNodeParameter('appId') as string;
+				const fields = this.getNodeParameter('fields') as string[];
+				const options = this.getNodeParameter('options') as IDataObject;
+
+				const body = {
+					object: snakeCase(object),
+					callback_url: webhookUrl,
+					verify_token: uuid(),
+					fields: fields.includes('*') ? getAllFields(object) : fields,
+				} as IDataObject;
+
+				if (options.includeValues !== undefined) {
+					body.include_values = options.includeValues;
+				}
+
+				const responseData = await facebookApiRequest.call(
+					this,
+					'POST',
+					`/${appId}/subscriptions`,
+					body,
+				);
+
+				webhookData.verifyToken = body.verify_token;
+
+				if (responseData.success !== true) {
+					// Facebook did not return success, so something went wrong
+					throw new NodeApiError(this.getNode(), responseData as JsonObject, {
+						message: 'Facebook webhook creation response did not contain the expected data.',
+					});
+				}
+				return true;
+			},
+			async delete(this: IHookFunctions): Promise<boolean> {
+				const appId = this.getNodeParameter('appId') as string;
+				const object = this.getNodeParameter('object') as string;
+
+				try {
+					await facebookApiRequest.call(this, 'DELETE', `/${appId}/subscriptions`, {
+						object: snakeCase(object),
+					});
+				} catch (error) {
+					return false;
+				}
+				return true;
+			},
+		},
+	};
+
+	async webhook(this: IWebhookFunctions): Promise<IWebhookResponseData> {
+		const bodyData = this.getBodyData();
+		const query = this.getQueryData() as IDataObject;
+		const res = this.getResponseObject();
+		const req = this.getRequestObject();
+		const headerData = this.getHeaderData() as IDataObject;
+		const credentials = await this.getCredentials('facebookGraphAppApi');
+		// Check if we're getting facebook's challenge request (https://developers.facebook.com/docs/graph-api/webhooks/getting-started)
+		if (this.getWebhookName() === 'setup') {
+			if (query['hub.challenge']) {
+				//TODO
+				//compare hub.verify_token with the saved token
+				//const webhookData = this.getWorkflowStaticData('node');
+				// if (webhookData.verifyToken !== query['hub.verify_token']) {
+				// 	return {};
+				// }
+				res.status(200).send(query['hub.challenge']).end();
+				return {
+					noWebhookResponse: true,
+				};
+			}
+		}
+
+		// validate signature if app secret is set
+		if (credentials.appSecret !== '') {
+			const computedSignature = createHmac('sha1', credentials.appSecret as string)
+				.update(req.rawBody)
+				.digest('hex');
+			if (headerData['x-hub-signature'] !== `sha1=${computedSignature}`) {
+				return {};
+			}
+		}
+
+		return {
+			workflowData: [this.helpers.returnJsonArray(bodyData.entry as IDataObject[])],
+		};
+	}
+}